ABSTRACT: Underlying
the current debate between simulation theory and theory theory is the assumption that folk
psychological explanations of behavior are causal. Simulationists Martin Davies, Tony
Stone, and Jane Heal claim that folk psychological explanations are explanations that make
sense of another person by citing the thoughts important to the determination of his
behavior on a given occasion. I argue that it is unlikely these explanations will be
causal. Davis et al. base their claim on the assumption that a certain isomorphism obtains
between the cognitive mechanisms of human beings. Investigation into the nature of the
isomorphism required reveals that it is of a sort that is unlikely to obtain. I suggest
that in order to maintain their challenge to theory theory, simulationists must either
motivate and describe a non-causal simulation-based account of folk psychological
explanation or else delineate a causal account that attributes a nonessential, heuristic
role to simulation.

I. Introduction

Much interest has been raised recently in cognitive science and in the philosophy of
mind by a debate that focuses on the nature of the cognitive mechanism that underlies our
folk psychological practices. One side in this debate is represented by proponents of the
reigning paradigm, the theory theory. Theory theorists say that our ability to give
explanations, predictions and interpretations of intentional behavior is subserved by
tacit knowledge of an internally-represented theory of commonsense psychology (Fodor
1987). The simulation theory challenges this view on the grounds that there is no evidence
to support the suggestion that we have such knowledge and some evidence to suppose that we
do not (Gordon 1986: Goldman 1989). It is more likely, say simulationists, that these
abilities are simply underpinned by the innate capacity to simulate others.

Simulationists argue that a compelling case can be made against the theory theory. I do
not discuss that case here. Instead I address an issue which, although crucial to the
outcome of the debate, has not yet been examined. This issue concerns the nature of the
commonsense psychological explanations produced by the mechanism whose functioning both
theories claim to describe.

Two assumptions bring the issue of explanation to the fore. One of these pertains to
the range and the other to the type of event that the theories are adduced to account for.
The merits of the theory theory and the simulation theory are usually discussed in
relation to the practice of the prediction of intentional behavior. The reasonable
assumption, (assumption A), is that the mechanism that is deployed in prediction will be
the same one that is deployed in the explanation, the description and the interpretation
of our own and others behavior. The second assumption, (assumption B), is that the
two theories offer competing accounts of the same sort of event. The theory theory and the
simulation theory, in proposing alternative views of the mechanism underlying our folk
psychological practices of prediction, explanation, etc., agree on what these practices
consist in.

With regard to explanation, the grounds for assumption B are not clear. Theory
theorists hold that the commonsense psychological explanations of behavior produced by
theory deployment are causal explanations. Those who think that the folk theory is
internally represented in the form of psychological laws have a ready-made model of causal
explanation available to substantiate this claim, the covering law model. Just like
explanations in basic science and in the special sciences, they point out, folk
psychological explanations are deductive arguments in which a commonsense psychological
covering law is implicitly deployed.

Simulationists are not explicit about the kind of explanations produced by simulation.
Nevertheless grounding assumptions A and B requires spelling out the conditions that a
correct simulation- produced folk psychological causal explanation of behavior satisfies.
Since simulation theory is founded on the premise that there is no body of
internally-represented commonsense psychological knowledge, and consequently no laws in
which it is represented, appealing to the covering law model of causal explanation is not
an option. What simulation needs in order to substantiate assumptions A and B is a causal
account of folk psychological explanation whose satisfaction conditions either involve
simulation essentially or, if they do not, are at least compatible with simulation as an
heuristic device for picking out what is the most likely to be the correct causal
explanation. In this paper I discuss a suggestion for explanation which assigns an
essential role to simulation.

In the next section, after laying out a general version of the simulation theory, I
describe a view that has been proposed recently both as a version of the simulation theory
and as a type of theory that stresses the idea of a distinctive kind of explanation. In
Section Three this simulation-based proposal for explanation is developed and in Section
Four the view is examined with regard to its potential to fill the simulationist need for
an account of causal explanation.

II. The Simulation Theory

A theme common to all versions of the simulation theory is that when we predict the
behavior of another person, or of ourselves at a time remote from the present, the
mechanism which governs the daily interaction of our beliefs, desires and other
intentional and qualitative states, the practical-reasoning mechanism, is disengaged from
its actual inputs, viz. from external stimuli and from our own salient beliefs and
desires. At the same time, this mechanism is disconnected from the action controllers, the
mental mechanisms responsible for a decision-to-behave being translated into actual
behavior. Operating "off-line" in this manner, the decision-making mechanism is
fed pretend-input in the form of those beliefs and desires we imagine we would instantiate
ourselves if we were in the situation of the person whose behavior we are about to
predict. The practical reasoning mechanism then processes these pretend inputs and a
pretend decision-to- behave is generated. This pretend decision-to-behave is transformed
into the prediction of behavior. Commonsense psychological explanations of behavior are
produced in a similar way, claim simulationists. In explaining a behavioral episode we
feed into our disengaged decision- making mechanism those beliefs and desires we imagine
are likely to produce a decision to perform the behavior we want to explain.

Martin Davies and Tony Stone (1996, p.136) pointed out recently that there is a type of
theory which qualifies as a version of the simulation theory under some construals of
simulation, and stresses the idea that commonsense psychological explanations are
explanations that "make sense of another person." According to this view, in
making a decision to act one "...bring[s] to bear [ones] knowledge about the
world, and arrive[s] at a judgement about what is the thing to do." Davies and
Stone admit that both knowledge and imagination are drawn upon here, but insist there need
be no intrusion into ones own decision taking of any body of empirical theory about
psychology  about what people in certain situations and with certain propositional
attitudes generally tend to do (1996, p.136). The same kind of normative judgment is
relevant when we explain or understand the behavior of another person, say Davies and
Stone. They agree with John McDowell that

[T]he concepts of the propositional attitudes have their proper home in
explanations of a special sort: explanations in which things are made intelligible by
being revealed to be, or to be approximate to being, as they rationally ought to be.(1985,
p.389)

Davies and Stone suggest that this type of theory may count as a variation on the
simulation theme according to Stich and Nichols way of drawing the "battle
lines." Stich and Nichols (1992, p.47) consider any theory that involves processing
in the decision-making mechanism when it is disconnected from its natural inputs and from
the action controllers ("off-line" processing) a version of the simulation
theory. Since the strategy described by Davies and Stone has the explainer feeding into
his own practical decision-making mechanism facts about the circumstances in which a
decision-to-behave was made by another and this mechanism generating a pretend
decision-to-behave which is not then translated into behavior, it does seem to meet Stich
and Nichols rather broad condition for simulation.

III. Explanations that Make Sense of Behavior

Davies and Stone do not address the issue of whether simulation-generated folk
psychological explanations that make sense of other people are causal. In this section I
suggest an account of folk psychological explanation based on Davies and Stones view
of the strategy deployed in explanation-giving and examine it with regard to its potential
to fill the simulationist need for an account of causal explanation. The suggestion is the
following:

(SE)* The statement that Philip smoked a cigarette because he believed that p
and desired that q is a correct explanation of his smoking a cigarette iff

(a) he smoked a cigarette,

(b) he believed that p and desired that q, and

(c) a decision to smoke a cigarette is the result of a simulation of Philip run
on the decision-making mechanism of the explainer and that simulation satisfies the
following conditions:

(i)the belief that p and the desire that q emerge from the simulation as the
belief and the desire whose instantiation in circumstances similar to those that obtained
when Philip decided to smoke a cigarette would make that decision intelligible to the
explainer

(ii) no other belief and desire emerge from the simulation as the belief and the
desire whose instantiation in those circumstances would make the decision to smoke a
cigarette more intelligible to him.

One simulationist who would be quick to point out that there are folk psychological
explanations of behavior that do not satisfy these, or any other, simulation-based
conditions is Jane Heal. Heal says that "...the only cases that a simulationist
should confidently claim are those where (a) the starting point is an item or collection
of items with content, (b) the outcome is a further item with content, (c) the latter
content is rationally or intelligibly linked to that of the earlier item(s)" (1996b,
p.56). Following Heal, let us suppose that the domain of explanations in which simulation
is essentially involved is limited in this way and see whether satisfaction of the
simulation-based condition at (SE)* is likely to be necessary and/or sufficient for a
correct one.

Let us take the case of Philip who decides to take up smoking and smokes his first
cigarette while working on his dissertation. Let us suppose that the correct commonsense
psychological explanation of Philips smoking is "Philip smoked because he wants
to finish writing his dissertation and he believes that he will write more easily while
smoking." Philips case clearly qualifies as a candidate for Heals type of
simulation in that his belief and his desire are contentful states that are intelligibly
linked to each other and to his decision to smoke. The next step is to examine what, in
Heals view, would be the case if this correct explanation were to satisfy the
simulation condition (c) at (SE)*.

Heal (1996b, pp.59-60) points out that recent thought in moral psychology and in the
philosophy of action more generally has developed a view about the conception of desires,
emotions and intentions which affects how we should conceive of simulating these states.
This conception emphasizes the links between the whole motivational and affective side of
our nature and the concept of the valuable: the desire that p, for example, should be
understood as being closely linked to conceiving that it would be valuable in some way,
enjoyable, health promoting, just, if p. Heal points out that since phenomena like
akrasia, depression and overreaction show that the strength of motivation or feeling can
get out of line with what is rationally licensed by the associated judgments, the states
in question cannot be identified with the value judgments. However, she adds, this does
not indicate that there is more to simulating a desire, an emotion or an intention
than entertaining the content of the associated value judgment. She points out that
"[A]s far as rationalizing and making intelligible are concerned it is the value
judgments that do the work" (1996b,p.60).

On this view then, the explanation of Philips smoking will satisfy (c) at (SE)*
iff the value judgment attached to his desire to finish his dissertation, i.e. that
finishing his dissertation would be a very good thing indeed, is correctly simulated such
that this desire emerges from a simulation of Philip, together with the belief that he
will write more easily while smoking, as the belief and the desire that make best sense of
Philips decision to smoke in the circumstances in which he actually made that
decision.

IV. The Question of Isomorphism

Heal suggests that what is responsible for our success in simulating is the remarkable
cognitive machinery with which we are endowed. This machinery, besides empowering us to
pick out from our own world view the factors relevant to any given problem, also
"enables us to pick out from anothers world view the particular thoughts
important to determining his or her behavior in a specified case" (1996a, pp.84-5).
She adds: "To apply the remarkable machinery to someone elses world view so as
to extract from it the thoughts relevant to answering a particular question is precisely
to simulate his or her thought." In dealing with others, in particular in predicting
their thoughts "we take account of the fact that they have the ability to cope
sensibly when other things are not equal or circumstances are not normal" (1996a,
p.81).

Heals claim about the role of simulation in our folk psychological practices
relies on two assumptions: first, that our cognitive machinery is such that we have the
capacity to simulate successfully the rationally-linked contentful states that another
instantiates on a specific occasion and, second, that the cognitive machinery responsible
for this competence is isomorphic, or relevantly similar, in human beings. It is with the
posited isomorphism or relevant similarity that I take issue here. It seems that even if
it is true that the cognitive structure in human beings is such that it allows some sort
of simulation, it does not follow that the cognitive machinery in question will be
strictly isomorphic, or even similar enough to account for the role that Heal attributes
to simulation. Below I discuss the question of the sort of similarity necessary in order
for one human being to pick out "from anothers world view the particular
thoughts important to determining his or her behavior in a specified case" (1996a,
p.84).

One possibility is that the similarity consists in the fact that the cognitive
mechanism incorporates some sort of norm of what it is for one thought to be rationally
connected to another and what it is for a thought to be rationally linked to behavior.
However it does not look as though our being similar in this respect will suffice to
account for our ability to explain rational behavior. Imagine the ideal case in which a
potential explainer, thus equipped, succeeds in simulating all of the relevant
contentful states that a similarly-equipped behaver instantiated on the occasion of his
decision to behave. What processing according to a norm might extract from the complex of
correctly- simulated mental states are those which, among all the ones the behaver
actually instantiated on the occasion of his decision to behave, are the most likely
to be instantiated by a rational behaver in relation to the kind of behavior in question
in circumstances of the type in question. There is no reason to believe that these are
what actually caused the behaviorial episode at issue. The posited isomorphism
between the cognitive mechanisms is simply too weak to support such a suggestion.

If we construe the similarity in cognitive machinery as strong to the degree
that it allows the rationally-linked contentful states causally relevant to a specific
behavior on a particular occasion to emerge from a simulation more often than not, the
issue about cognitive similarity becomes a question of the degree of similarity necessary
to account for our (apparent) success in explaining. I suggest that this degree is likely
to be implausibly high. For it seems that in order for these states to emerge from a
simulation the explainer must simulate correctly not just the content of the
behavers mental states and the rational links between them, but the ranking
in the value judgments attached to the behavers desires, emotions and intentions and
the hierarchy in the strength of the (relevant) beliefs that obtained at the moment
the behaver made his decision to behave.

To return to the case of Philip; if the desire to finish writing his dissertation and
the belief that he will write more easily while smoking are to emerge from a simulation of
Philip as those that are explanatorily relevant to his decision to smoke, then the
simulator will succeed in at least the following tasks. Besides simulating the
content of the value judgment attached to Philips desire to finish his dissertation,
viz., that finishing it would be a very good thing indeed, he/she will simulate the
ranking of this value judgment in relation to the value judgments attached to any other
state in the inter-related complex of relevant states that Philip instantiated at the time
he made the decision to smoke, viz., that finishing his dissertation ranked higher for
Philip in the circumstances in which he made the decision to smoke than, for example, the
value judgments attached to his firm intention not to expose his two-year old to the
noxious effects of second-hand smoke, to his deep-seated fear of becoming addicted to
nicotine and to his standing desire to preserve his chances to live a long and pain-free
life. The simulator will also simulate successfully the degree of strength carried by
Philips belief about smokings effect on his writing in relation to his other
beliefs about writing and about smoking and, if it is true, as Heal (1996a. p.79) says,
that "no thought, whatever its subject matter, can be ruled out a priori as certainly
irrelevant to a given question," even in relation to indeterminately many of his
other beliefs .

So it turns out that Heals suggestion that our cognitive machinery "enables
us to pick out from anothers world view the particular thoughts important to
determining his or her behavior in a specified case" presupposes a degree of
similarity between the cognitive mechanisms of human beings that is likely to be much
higher than the degree required to simulate the content and the rational links between
anothers beliefs, desires, etc., and associated value judgments. This degree needs
to be such that it allows one person to simulatethe "weighting" that
another attributed to a large section of his/her inter-related complex of mental states on
a specific occasion. That the cognitive mechanisms of human beings are similar to a degree
that allows this sort of simulation is far from self-evident.

This finding has important ramifications for the simulation-theory theory debate. If,
as Davies, Stone, and Heal say, folk psychological explanations are explanations that make
sense of behavior and involve simulation essentially, and if the degree of similarity
required for the explainer to cite the states causally responible for the behavers
behavior is unlikely to obtain, then it is unlikely that folk psychological explanations
are causal. In this case the assumption that the simulation theory and the theory theory
are accounting for the same type of explanation-giving (assumption B), i.e. causal
explanation-giving, will be unfounded. Simulationists will need to say both why they think
folk psychological explanations are not causal and to spell out the conditions that a
correct simulation-involving non-causal folk psychological explanation that makes sense of
behavior satisfies.

A different, and less radical, way to save the suggestion of Davies et al. involves
attributing a non-essential role to simulation in explanation. If the role of simulation
in explanations that make sense of behavior is to merely pick out from a range of
belief-desire sets the one that is the most likely to be the correct causal explanation,
then simulation will not be essentially involved in the conditions that the correct causal
explanation satisfies. Our remarkable cognitive machinery being such that it allows us
pick out the correct explanation often enough to account for our successful interaction
does not entail simulation being either necessary or sufficient for a correct explanation
that makes sense of behavior. If simulationists take this route they will still owe us a
causal account of folk psychological explanation, one that is both compatible with the
simulation heuristic and, if they wish to maintain their challenge to the theory theory,
does not appeal to an internally- represented tacitly-known theory of folk psychology.

References

Davies, M. 1994. The Mental Simulation
Debate. In C. Peacocke (ed.), Objectivity, Simulation and the Unity of Consciousness:
Current Issues in the Philosophy of Mind: Proceedings of the British Academy, 83.
Oxford University Press: Oxford. 99-127.